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| BYD K9 electric bus in London |
The Bangalore Metropolitan Transport Corporation has recently
started trial runs of Electric Buses for its vast public transportation
network. Electric Buses are slowly gaining acceptance and have been adopted in
few cities around the world. The most popular of these buses is the E9 –
manufactured by BYD – a popular Hong Kong based battery and automobile company. Electric buses are commercially in use at various places in
China. They are in trial at Utah, Chile, London, South Korea.
The
batteries that BYD uses are Lithium Iron Phosphate,
developed in-house. These give a range of 250km per charge, which is
quite
respectable for a day’s intra-city route. They can be charged in 6 hours
at
normal rate and 3 hours for a quick charge. Ideally electric city buses
can be
fully charged overnight or given short bursts of high speed charging
during
terminal stops. Another possibility is wireless induction charging. Read more about that here. It consumes 100 kWh in an hour
and that translates to just Rs.4
per km, as compared to Rs.20 per km in diesel buses. The battery is
expected to
last 6000 recharging cycles or 1.5 million kms, thereby capable of
saving
nearly a crore of rupees before a battery swap. This is considering the
fact
that there are hardly any maintenance costs in electric vehicles. Unlike
petroleum operated vehicles, they do not have filters, oil changes,
turbochargers, etc. These expenses are a lot in heavy vehicles like
buses, and
the time taken to service also accounts for revenue loss. In fact there
is only
one moving part in the electric motor.
Electric buses are an ideal choice for cities with dense
traffic and otherwise too. They are very silent. A V8 roar may be appreciable
in a sports car, but an old bus noisily accelerating and blowing soot on your
face is never charming. Apart from that,
electric buses have regenerative braking. This is a technology that helps
vehicles recover the kinetic energy of motion that is otherwise lost during
braking. What happens is when the foot is left off the accelerator, the motor
acts in reverse as a generator using the motion to top up the excess energy
into the batteries. This also reduces the need of brakes in predictable
situations (Bus routes = more predictable), thereby elongating the life of
brake pads and shoes by a huge margin. This technique is very useful in
stop-start situations which are very high in dense city traffic. Going
downhill, a Mahindra Reva e2o (an electric car from India) has been able to
recover 20% more range on the return journey on a particular trip to hilly
region.
Then there is the usual electric advantage of not wasting
fuel at traffic stops – they use energy when the accelerator is pressed. Hence
there is no wastage of energy like internal combustion engines which have to
kept on during idling and consume fuel in that process. This is particularly
beneficial in dense cities and typically for buses as they stop for loading and
unloading of people. This frequent dis-acceleration also helps in regenerative
braking. Also electric motors produce 100% torque at 0 rpm. This high torque
nature is more suited to heavy vehicles like buses and trucks.
With rising costs of polluting petroleum, the operating cost
difference will widen further for sure. Electric buses at present scenario are able
to recover the initial investment fast too. A proper charging infrastructure is
highly necessary. The grid needs to get greener. Dirty coal needs to be
replaced with renewable sources like hydro, solar and wind energies. Karnataka produces
a fair share of green electricity. These
low floored, air conditioned electric buses will go head-on with the
red Volvo city buses and are expected to be even more comfortable than
them. They will also make the
Bangalore air more breathable. We hope this model is a success and it is replicated in more
cities throughout the country.
